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Programmable Relay Gets an HMI

June 10, 2008

Almost Every Industrial Manufacturer Faces Mounting Pressure to Increase Production While Reducing Waste and Maintenance Downtime and to Do It All with a Shrinking Workforce

Those customers are looking to their industrial OEM partners for flexible control systems that perform multiple operations requiring minimal troubleshooting and maintenance.

Siemens Energy & Automation believes it has met these control system needs with the Logo! TD text display HMI, the newest addition to the Logo! line of programmable relays.

The text display panel provides an affordable HMI for equipment builders and their customers, even on the simplest relay control systems. By having a display panel with built-in operator functions and diagnostic messages customized for their processes, end users can make quick adjustments or more easily troubleshoot failures.

Paul Ruland, Siemens’ product marketing manager, says the Logo! TD addresses the challenges OEMs face when migrating a basic hardwired control design—pushbutton/pilot devices, rotary timers, counters and cube relays—to a programmable controller. In most cases, they need only a programmable relay with a simple interface for operators to adjust settings and view status.

“But the choice can sometimes unnecessarily force a simple design into a full PLC system if an operator interface also is required,” says Ruland. “The display satisfies OEMs’ requirements for eliminating hardwired controls and providing smaller enclosures with fewer pilot devices. End users enjoy simplified operator control, machine status readings and improved diagnostics for easy troubleshooting.”

The new text display is a backlit LCD with a 128x64 pixel resolution capable of displaying four lines of text with up to 12 characters per line. With a built-in horizontal and vertical bar-graph display feature, viewing options are not limited to text-only. The bar-graph display modes can be configured to represent any numeric value in the Logo! controller, including an attached tank level sensor, flow rate, rpm, counts, time, cycles and more.

Additional display capabilities include a text ticker feature that can scroll up to a 24-character text message horizontally across the screen. The unit also includes six buttons for screen navigation and data entry, along with four user-function buttons configurable for any desired equipment operation. The display is designed in an IP65 case rated for NEMA 4/4X indoor washdown environments and is certified with industry standard agency approvals, including cUL US, Factory Mutual Class 1 Div 2 and C-Tick.

“This display is part of the seventh-generation Logo! line that includes the new Logo! Soft Comfort version 6.0 Windows configuration software,” says Ruland. “All Logo! control functions and Logo! TD screens are developed in one Soft Comfort user program, eliminating the need to maintain separate PLC and HMI programs.”

Additional software enhancements, adds Ruland, include special analog math functions, increased message and program memory, improved software simulation features and built-in pulse-width modulation (PWM) function for heater control applications.

Programmable relays are a great fit for highly mechanical equipment applications where only a little electrical control is required, adds Greg Marsh, Siemens’ senior application engineer. “These equipment providers often are able to develop an entire control system based on the new Logo! TD display,” he says.